Contour Enthusiasts Group Archives Forums General General 10w30 or 5w30 Mobil1 post your reasoning

Oil weight primer:

What the heck does 5W-30 or 10W-30 mean. The first part 5W or 10W is the cold weight. So a 5W oil is flows better at colder temp than does a 10W oil. The 30 is essentially the viscosity at a specific operating temperature.

In the summer time, I would be more comfortable with a 10W-30, especially if it is a traditional (non-synthetic oil). Why? Because there are fewer viscosity index improvers in the 10W-30 oil. There is less spread between the two weights. For a synthetic, this is not as much of an issue, but still an issue to some extent.

Viscosity, or a measure of a fluids resistance to flow is improved by these VI. However, these additives do nothing to actually lubricate the parts that spin and rub in your engine.

(Which is why I prefer a synthetic oil, fewer additives to make the lubricant behave, flow and resist acids, relative to conventional oils.)

So I think you would be fine with either a 5W30 or a 10W30 oil. If I were not using a synthetic, I would use a 10W30 in the summer and a 5W30 in the winter.

FWIW,

TB